1. Field of the Invention
The present invention relates to bicycle accessories and more particularly to a lighting fixture for use in a bicycle.
2. Description of the Related Art
A bicycle lighting fixture enhances bicycle riding safety. More particularly, when riding a bicycle at night, in a tunnel, or under an insufficient lighting environment, the lighting fixture on the bicycle provides lighting for enabling the bicycle rider to see the road condition and alerting vehicles in the opposing direction. In order to achieve the aforesaid targets, some countries and areas define standard regulations on bicycle lighting fixtures. Among them, German defines strict rules on bicycle lighting fixtures so thoroughly as to ensure a high level of safety. The related German standard is called “TA23” and it's found within StVZO (anything related road & traffic). Imagine a wall 10 m away from the light and 90 deg to the beam. The wall is at least 2.8 m wide and 2 m high and split into multiple measurement zones. The beam pattern seen on the wall will typically have a very bright spot in the middle and go darker to the left and right as well as down. The brightest spot has to be 10 Lux min. In the area above the hotspot, the intensity must not exceed 2 Lux as not to disturb oncoming traffic. Table I illustrates the related data.
TABLE IUnit: lx−8°−4°0°4°8°>3.4°<2   0°>50%[0°, 0°]>20>50%[0°, 0°]−1.5°>50%[0°, 0°] −5°>2>2  >2.5>2>2
In order to meet the rules of StVZO “TA23”, EP2157009 discloses a bicycle headlamp entitled “Bicycle headlamp with near field illumination and corresponding bicycle”, as illustrated in FIG. 6, wherein the reflector (3) provides multiple reflecting surfaces of different curvatures at different locations so that the illumination of a specific luminous area meets the rules of StVZO “TA23”.
This design of bicycle headlight has a light source with an irradiant reflector of the light source. A light disk of the reflector forms a light, which comprises a horizontal datum plane that is appropriate for vertically largest light intensity in a range. The reflector is formed such that the width of the light cone remains constant up to a range of 15 degrees below the horizontal datum plane. This design of the reflecting surfaces of the reflector complicates the design and fabrication of the shape-forming mold for reflector. In consequence, the fabrication of the reflector requires much labor and time, increasing the manufacturing cost.